Two-part power referencing for an efficient serially coordinated distributed flexible power point tracking of photovoltaic plants

Abstract

The objective of this paper is to make an efficient implementation of distributed flexible power point tracking (D-FPPT) by creating a suitable power referencing coordination among individual power tracking controllers. Performing power tracking in a distributed manner is helpful in reducing the capacity mismatch loss under partial shading, whereas the flexible power point tracking makes it possible to adjust the photovoltaic power output with a greater freedom. Apart from getting a suitable converter topology, the D-FPPT control also requires a coordinated dynamic adjustment of subarray power reference commands so as to avoid any artificial power scarcity. A serial coordination is, usually, advantageous over the centralized coordination as the former greatly reduces the complexity of the inter-controller communication. Although a simple serially coordinated absolute power referencing scheme has already been proposed in the literature, the particular scheme was found to have the problem of very long power tracking transients even without partial shading. Therefore, in order to make D-FPPT adaptive to the environmental condition, a novel serially coordinated incremental power referencing scheme is proposed in this paper. Extensive physical experiments are carried out to compare the practical performances of proposed and existing power referencing coordination schemes for D-FPPT.